Flanging machine and method for spin-flanging workpieces

ABSTRACT

A crimping device ( 1 ) comprising a crimping bed ( 12 ) provided for receiving a workpiece ( 10 ), a multiaxial manipulator, in particular an industrial robot ( 2 ), which has a crimping tool ( 5 ) with at least one crimping roller ( 6 ) on its hand, is intended to avoid fold formation on the flange ( 11 ), particularly during the pre-crimping. To this end, at least parts of the crimping roller ( 6 ) have the form of a cone or a truncated cone having an axis of symmetry ( 27 ), an apex ( 26 ), and an opening angle α, wherein for the opening angle α of the cone it holds that 180°&gt;α≧140°.

The invention relates to a crimping device comprising a multiaxialindustrial robot, in particular an industrial robot which has a crimpingtool with a crimping head on its hand and at least one crimping rollerlocated on the crimping head.

Such a crimping device is known, for example, from DE-U-299 10 871. Therobot-guided crimping tool disclosed therefore has a crimping roller bywhich means a crimping flange is folded over and pressed down on aworkpiece. The pre- and finish-crimping can optionally take place in aplurality of operations.

When using such a crimping device, however, the formation of folds inthe material of the flange frequently occurs during the pre-crimping.These folds must be eliminated to prepare a defect-free surface in thefinish-crimping step, which however is typically only possible in arestricted scope and additionally requires expenditure.

It is therefore the object of the invention to provide a crimpingdevice, which allows fold-free crimping of workpieces in the simplestpossible manner.

In addition, it is a further object of the present invention to providea method for roll crimping of workpieces, by which means the formationof folds can be reliably avoided.

According to the invention, this object is achieved with the subjectmatter of the independent patent claims.

Advantageous further developments of the invention are the subjectmatter of the dependent claims.

An inventive crimping device comprises a crimping bed provided forreceiving a workpiece and a multiaxial manipulator, in particular anindustrial robot, which has a crimping tool with at least one crimpingroller on its hand. At least parts of the crimping roller have the formof a cone or a truncated cone having an apex, an axis of symmetryrunning through said apex, and an opening angle α, wherein for theopening angle α of the cone it holds that 180°>α≧140°.

The invention starts from the consideration that fold formation duringpre-crimping should be avoided a priori. As has been shown inexperiments and in simulations, fold formation can be attributed tolocal elongations of the material, particularly in the vicinity of theflange edge, during pre-crimping.

Particularly in the area of the flange edge, the local elongation of thematerial should therefore be kept relatively low. The elongation whichcomes about due to the flange material “winding round” the crimpingroller, can be reduced particularly in the area of the flange edge byselecting the crimping roller to be a conical one instead of theconventional cylindrical crimping roller, wherein “conical” is used hereand subsequently as an abbreviation and means a crimping roller whicheither has the shape of a full cone or that of a truncated cone or whichhas the shape of a full cone or that of a truncated cone at least insome areas.

As a result of its straight guidance by the robot, such a conicalcrimping roller does not roll on the entire circumferential surface ofthe cone but strictly speaking, only on a circle line. The other areasof the circumferential surface exert a significantly lower pressingpressure on the flange. Thus, the pressing pressure has a gradient alonga section on the circumferential surface between the base area and theapex of the cone, which is suitable for preventing local elongations ofthe flange edge.

As has been found, the strength of the gradient in the pressing pressureis optimal when the opening angle α of the cone is at least 1400,preferably at least 1600.

In addition to the opening angle of the cone, further parameters suchas, for example, the diameter of the crimping roller are important foravoiding local elongations. The base area of the conical crimping rolleradvantageously has a diameter d of at least 60 mm.

In one exemplary embodiment of the invention, the conical crimpingroller is provided as a pre-crimping roller and a cylindrical furthercrimping roller is provided as the finish crimping roller. However, thecrimping roller can also be configured such that it has a conical orfrustro-conical region and in addition, a cylindrical region so that itcan be used as a pre-crimping roller and as a finish-crimping roller.

The crimping roller is advantageously disposed fixedly on a driven shaftof a drive, by which means the crimping roller can be driven at adefined rotational speed during the crimping. The direction of rotationof the crimping roller takes place in the direction of the travelingindustrial robot, wherein the rotational speed of the crimping roller ishigher than the traveling speed of the industrial robot.

The friction between the crimping flange to be crimped and the surfaceof the crimping rollers machining the crimping flange should be as highas possible. “Spinning” of the driven crimping rollers on the crimpingflange should be avoided under all circumstances. In this case, it hasbeen found to be an expedient embodiment for the crimping rollers tomake the crimping rollers of a hard metal core, preferably a steel, witha hard rubber cladding located thereon. The hard rubber cladding can bevulcanized thereon.

The inventive apparatus has the advantage that the flange material isless severely locally elongated than by conventional crimping rollersdue to the optimized conical geometry of the crimping roller. As aresult, fold formations on the workpiece occur less frequently and alsoexpensive efforts to reduce the folding during finish crimping or areduction in the translational speed can be dispensed with.

According to the present invention, a method for the roll crimping ofmetal parts comprises the following steps: firstly, a workpiece to becrimped is provided with a flange located on a crimping bed. The flangeis pre-crimped with a pre-crimping roller guided by a multiaxialmanipulator, for example, an industrial robot, the pre-crimping rollerhas the shape of a cone or truncated cone, having an axis of symmetry,an apex and an opening angle α, and the opening angle α of the cone isat least 140°. The flange is then finish-crimped, preferably with acylindrical finish crimping roller.

Due to the optimized conical geometry of the crimping rollers, lesssevere local elongations than in conventional methods, which could leadto fold formation, occur particularly in the proximity of the flangeedge. In this case, there are two possibilities for the guidance of thecrimping roller:

Either the axis of symmetry of the conical crimping roller isapproximately perpendicular to the plane of the crimping bed during thecrimping process. In this case, “approximately perpendicular” means thatthe axis of symmetry passes through the plane of the crimping bed at anangle of greater than 45°.

In this case, the axis of symmetry of the pre-crimping roller isadvantageously turned through an angle g in the counterclockwisedirection toward the perpendicular to the direction of translation.

However, the axis of symmetry of the conical crimping roller can also beapproximately parallel to the plane of the crimping bed during thecrimping process. In this case, “approximately parallel” means that theaxis of symmetry passes through the plane of the crimping bed at anangle of less than 45°.

In this second case, the axis of symmetry of the pre-crimping roller isadvantageously turned through an angle g in the clockwise directiontoward the perpendicular to the direction of translation.

Before the beginning of the pre-crimping, the flange angle γ between theflange and the crimping bed and therefore the plane of the workpieceshould therefore be at most 90°.

The translational speed v₁ at which the crimping roller is guided duringthe pre-crimping is advantageously between 1000 mm/s and 1600 mm/s. Aplurality of pre- or finish crimping steps can be provided both for thepre- and finish-crimping of the flange.

The crimping device is particularly suitable for the roll crimping ofvehicle parts such as automobile doors, hoods, and tailgates.

Exemplary embodiments of the invention are explained in detailhereinafter with reference to the appended figures.

FIG. 1 shows in schematic side view a crimping device with an industrialrobot and a crimping tool with a driven crimping roller;

FIG. 2 shows schematically a crimping roller according to a firstembodiment;

FIG. 3 shows schematically a crimping roller according to a secondembodiment;

FIG. 4 shows schematically a crimping roller according to a thirdembodiment;

FIG. 5 shows schematically a side view of the crimping roller during thecrimping process;

FIGS. 6 and 7 show two possibilities for carrying out the roll crimping.In this case,

FIG. 6 a shows schematically a side view of a first possibility;

FIG. 6 b shows schematically the first possibility from anotherperspective;

FIG. 7 a shows schematically a side view of a second possibility;

FIG. 7 b shows schematically the second possibility from anotherperspective

The same parts are provided with the same reference numerals in all thefigures.

FIG. 1 shows in a schematic diagram a crimping device 1, whichprincipally consists of a six-axis industrial robot 2 and a crimpingtool 5.

The crimping tool 5 is moved by the industrial robot 2 with respect to aworkpiece 10 having one or more crimping flanges 11, which is disposedin a fixed position on a framework and clamped there on a crimping bed12.

The framework can also be designed as a rotary table (not shown), onwhich the crimping bed 12 is mounted, wherein the rotary table is turnedin the direction opposite to the direction of travel of the robot andfor this purpose is incorporated in the controller of the industrialrobot 2 or accesses a common controller.

The industrial robot shown in FIG. 1 has six axes of rotation. However,the number of axes can be smaller or larger. The industrial robot 2 hasa robot controller 13, by which means its movements, and optionally alsothe process sequence of the crimping, can be controlled and regulated.To this end, a movement sequence of the robot 2 and the crimping tool 5derived from the contour of the clamping flanges is programmed in therobot controller 13 and the CAD and/or CAM data of the workpiece 10 isstored in a random access memory.

The industrial robot 2 has a rocker arm and an outrigger 3, having arobot hand 4 with one or more movement axes disposed at its front end.On the driven side, the robot hand 4 has a hand flange to which thecrimping tool 5 is flange-mounted.

The crimping tool 5 shown in FIG. 1 has a crimping roller 6. Thecrimping roller 6 is firmly fastened to a driven shaft 7. The drivenshaft 7 is in communication with a transmission 8, which isflange-mounted to a drive motor 9. Transmission 8 and drive motor 9 arelocated inside the crimping tool 5.

In order to execute the roll crimping on the workpiece 10, theindustrial robot 2 is set in motion by the controller 13 and travelsaround the crimping flange 11 at a speed v₁. At the same time thecrimping roller 6 is pressed onto the crimping flange so that thecrimping roller 6 folds the crimping flange downward. The crimpingroller 6 is thereby set in rotational movement, which is effected viathe drive motor 9, the transmission 8, and ultimately the driven shaft7. The rotational movement of the crimping roller 6 is effected in thedirection of travel of the robot 2 along the outer contour of thecrimping flange 11.

The rotational speed v₂ or the rotational speed of the crimping roller 6is in this case greater than the speed of travel v₁ of the moving robot2. Accordingly, it holds that v₂>v₁. The speed v₁ of the industrialrobot 2 is typically between 1000 mm/s and 1600 mm/s.

As a result, the workpiece in the area of the crimping flange 11 ispulled by the crimping roller 6 slightly in the direction opposite tothe direction of travel of the robot 2. Any bunching of the workpiece 10in the area of the crimping flange 11 is thereby reduced.

The industrial robot 2 has a robot controller 13, which measures andadjusts the movements and the entire process sequence of the rollcrimping executed. The robot controller 13 is designed as acomputer-aided controller with one or more processors, a plurality ofinterfaces for input and output of data, and a plurality of memories foroperating, process, and other relevant data.

The track course and the corresponding movement sequence of theindustrial root 2 and of the crimping tool 8 are programmed in the robotcontroller 13 and stored in a random access memory.

In the area of its crimping head 15, the crimping device 1 has ameasuring device 20 which measures the crimping values detected from thecrimping process. The measuring device 20 is connected to the robotcontroller 13 via a line 19. The robot controller 13 is in turnconnected to the industrial robot 2 by means of a line 21.

The measuring device 20 in particular measures the rotational speed andthe pressing pressure of the crimping roller 6 during the roll crimpingand readjusts this by means of a desired value/actual value comparison.The readjustment in particular takes account of the exact adjustment ofthe rotating crimping roller 6.

Since the speed of travel of the robot 2 during travel around andprocessing of the workpiece 11 can be different, the rotational speed ofthe driven crimping roller 6 must be matched to this. This matching isalso carried out via the robot controller 13, in which the rotationalspeed of the crimping roller 6 is adjusted by means of the program datastored in the random access memory depending on the speed of travel ofthe robot 2.

In order to effectively prevent the bunching of the workpiece 10 in thearea of the crimping flange 11, which leads to fold formation at thecrimping flange 11, the crimping roller 6 has a special geometry.

FIGS. 2, 3, and 4 show schematically alternative embodiments of thecrimping roller 5.

The crimping roller 6 according to FIG. 2 has the form of a cone havinga circumferential surface 14 and a base area 16. The geometry of thecone is characterized by its opening angle α and the diameter d of itsbase area 16. An opening angle α of at least 140° is particularlyfavorable for avoiding fold formation. The diameter d is at least 60 mm.

The crimping roller 5 can either have the form of a full cone, as shownin FIG. 2. However, it can also have the form of a truncated cone, asshown in FIG. 3. The conical or frustro-conical roller 6 is used forpre-crimping the workpiece 10. A cylindrical finish-crimping roller, notshown, can be used, for example, for the finish-crimping.

However, the operations of pre- and finish crimping can also be executedwith a single crimping roller 6. For this, the crimping roller accordingto FIG. 4 has a conical region 25 for pre-crimping and a cylindricalregion 23 for finish-crimping. Both the pre- and the finish-crimping canbe executed in several passes.

FIG. 5 shows schematically a side view of the conical crimping roller 6and the crimping flange 11 during the crimping process.

The crimping roller 6 is set so that in a first region 18, it is pressedwith relatively high pressing pressure onto the crimping flange 11 andnestles closely against this flange. In a second region 22, which liescloser to the apex, the radius of the crimping roller 6 is significantlysmaller as a result of its conical geometry and the circumferentialsurface 14 of the cone does not nestle so closely against the crimpingflange 11 in this second region 22. The crimping roller 6 does roll onits entire circumferential surface 14 but strictly speaking, only on acircle on the circumferential surface.

Local elongations, which can lead to fold formation in the crimpingflange 11, come about due to the “winding around” of the flange materialaround the crimping roller 6. As a result of the smaller radius in thesecond region 22, which lies closer to the apex, the cone geometryresults in a particular small local elongation in the proximity of theflange edge 24.

The flange 11 forms a flange angle γ with the plane of the workpiece 10.Before the beginning of the pre-crimping, this flange angle γ should beat most 90°.

FIGS. 6 and 7 show two different possibilities for guiding the crimpingroller 6.

In FIG. 6 a the axis of symmetry 27 of the conical crimping roller 6lies approximately parallel to the plane of the crimping bed 12 andtherefore substantially also to the surface of the workpiece 10. Theapex 26 is facing the workpiece 10. “Approximately parallel” means inthis case that the axis of symmetry 27 passes through the plane of thecrimping bed 12 at an angle of less than 45°.

In this alignment of the crimping roller 6, the angle β, as shown inFIG. 6 b, according to the mathematical definition should be negative,that is, it should have come about through a clockwise rotation from theperpendicular 28 to the direction of translation v₁.

In the alternative possibility according to FIG. 7 a, the axis ofsymmetry 27 is approximately perpendicular to the plane of the crimpingbed. “Approximately perpendicular” means in this case that the axis ofsymmetry 27 passes through the plane of the crimping bed 12 at an angleof greater than 45°.

In this alternative alignment of the crimping roller 6, the angle β, asshown in FIG. 7 b, according to the mathematical definition should bepositive, that is, it should have come about through a counterclockwiserotation from the perpendicular 28 to the direction of translation v₁.

REFERENCE LIST

-   1 Crimping device-   2 Industrial root-   3 Outrigger-   4 Robot hand-   5 Crimping device-   6 Crimping roller-   7 Driven shaft-   8 Transmission-   9 Drive motor-   10 Workpiece-   11 Crimping flange-   12 Crimping bed-   13 Robot controller-   14 Circumferential surface-   15 Crimping head-   16 Base area-   17 First region-   18 Line-   19 Measuring device-   20 Line-   21 Second region-   22 Cylindrical region-   23 Flange edge-   24 Conical region-   25 Apex-   26 Axis of symmetry-   28 Direction perpendicular to v₁-   α Opening angle-   β Angle of travel-   γ Flange angle-   v₁ Translational speed

1. A flanging machine comprising: a flanging bed adapted to receive aworkpiece; and a multi-axle manipulator adapted to carry a flanging toolat a hand with at least one flanging role, wherein at least one part ofthe flanging role has a form of a cone with an apex, an at leastsubstantially symmetrical axle running through the apex, and an apexangle α of a specified surface area to be pressed on a flared flange,wherein the apex angle α of the cone is in a range of about 180°>α≧140°.2. The flanging machined according to claim 1, wherein that the range isabout 180°>α≧160°.
 3. The flanging machined according to claim 1,wherein a base area of the flanging role has a diameter d with d≧about60 mm.
 4. The flanging machined according to claim 1, wherein theflanging role is a pre-flanging role.
 5. The flanging machined accordingto claim 1, which comprises an additional flanging role adapted forfinal-flanging processes, wherein the flanging role has a cylindricalform after the final-flanging processes.
 6. The flanging machineaccording to of the claim 1, wherein the flanging role is adapted foruse in pre-flanging and final-flanging processes.
 7. A method tospin-flanging workpieces, comprising the steps of: provisioning of theworkpiece to be flanged with a flange on a flanging bed; pre-flanging ofthe flange with a pre-flanging role that has a conical form and isguided by a multi-axle manipulator, wherein for the apex angle α of alateral surface of the cone to be pressed on the flared flange it is inthe range of about 180°>α≧140°; and final-flanging of the flange.
 8. Themethod according to claim 7, wherein the final-flanging is carried outwith a final flanging role having a cylindrical form.
 9. The methodaccording to claim 7, wherein a local strain caused by the flanging roleis at its lowest at the at an edge of the flange and has a gradient fromthe edge of the flange to a beginning of the flange.
 10. The methodaccording to claim 7, wherein the symmetrical axle of the flanging roleis oriented in a substantially vertical position relative to a surfaceof the flanging bed.
 11. The method according to claim 10, wherein thesymmetrical axle of the flanging role is turned anti-clockwise by atraveling angle β in relation to a vertical of a translationaldirections.
 12. The method according to claim 7, wherein the symmetricalaxle of the flanging role is substantially parallel to a surface of theflanging bed.
 13. The method according to claim 12, wherein thesymmetrical axle of the flanging role is turned clockwise in relation tothe vertical of the translational direction v1 by a traveling angle β.14. The method according to claim 7, wherein the flanging role is guidedwith a translational velocity v1 during the pre-flanging, and thetranslational velocity v1 has a range of about 1000 mm/s≦v1≦1600 mm/s.15. (canceled)